The world premiere of “Mercy Falls,” the comedy New England playwright Jeni Mahoney shaped during Port Townsend’s PlayFest, comes this month to Key City Public Theatre.

The show arrives Nov. 29 and runs through Dec. 29 at the Key City Playhouse, 419 Washington St.

Come mid-December, “Mercy” plays in repertory with “Spirit of the Yule,” the original holiday musical about a real-life woman entrepreneur in Port Townsend.

“Mercy” Showtimes are 7 p.m. Fridays, Saturdays and Thursdays and 1 p.m. Sundays, with an extra 2:30 p.m. matinee added Dec. 27.

Tickets are $24 to $29, while information is available at KeyCityPublicTheatre.org and 360-385-5278.

Pay-what-you-wish performances are set for 1 p.m. Sunday, Dec. 1, and 7 p.m. Thursday, Dec. 5, when theater-goers should arrive up to 30 minutes ahead of time to claim their seats.

“Mercy Falls” is a fictional town, and the story “takes place in its own separate world; kind of a cockeyed world,” said Mahoney. She flew out in mid-November from her home in Merrimack, New Hampshire, to spend a week here as rehearsals ramped up.

“Mercy Falls” is all about Marcy Wuggelson, a woman who’s pretty much a perpetual jinx. On Christmas Eve, she goes to visit her favorite self-help author, Wanda Moore, in the hospital. There, she walks into a situation ripe for disaster, with a cast of characters including a nurse dressed as one of Santa’s reindeer and an unconventional nun. This, Mahoney said, just might be the moment when her luck is about to change.

“We’re laughing a lot. These guys are so funny,” she said of rehearsals with director Denise Winter, Consuelo Aduviso Brennan as Marcy, Michelle Hensel as Wanda and Tomoki Sage, Maggie Jo Bulkley and Jen True as a variety of characters.

The playwright is an Indie Theater Hall of Fame inductee and the author of plays including “Kandahar,” “Come Rain or Come Shine,” “The Feast of the Flying Cow … and Other Stories of War” and “Bad Water Juju.”